Compounding of thermoplastic polymers is commonly carried out by the addition of numerous mineral fillers, which are employed to enhance physical properties, improve the material processing characteristics, and lower the material cost. Such fillers include, calcium carbonate. magnesium hydroxide, barium sulfate, magnesium silicate et al. Such mineral fillers are commonly processed to a fineness, in which 1-100% of the material will pass a 325 or finer mesh screen.
Additionally, it is common practice to add and suspend similar mineral fillers of similar or coarser particle size described above to latex or acrylic based emulsions, polyurethane, plastisol polyvinyl chloride and ethylene vinyl acetate hot melt adhesives which are commonly used to pre-coat and back coat textile, rug and carpet constructions so that such constructions are imparted with useful mechanical properties but with significantly improved economics and high post consumer content. Such latex and acrylic based emulsions, polyurethane, plastisol polyvinyl chloride and ethylene vinyl acetate hot melt adhesives can be used to also permanently adhere one layer of the construction to another layer resulting in desired end use properties such as dimensional stability, stiffness and abrasion resistance. Typically, when you disperse or suspend higher levels of a mineral filler into polymer melts, emulsion type polymers, or polymer solutions, the filler will stiffen the polymer composition and cause the polymeric composition to harden (increase in the shore hardness for example) relative to increased concentration levels of the fillers.